Method and means for air conditioning



March 27, 1945, F. R. BICHOWSKY METHOD AND MEANS FOR AIR CONDITIONING 2. Sheets-Sheet l Filed Aug. 21, 1940 INVENTOR F. R. BICHOWSKY March 27, 1945.

FUR. BICHOWSKY METHOD AND MEANS FOR AIR CONDITIONING Filed Aug. 21, 1940 2 Sheets-Sheet 2 ooooooo wfiflooooooow oo ooom FIG. 2.

INVENTOR.

F. R. BICHOWSKY FIG. 3.

Patented Mar. 27, 1945 UNITED STATES PATENT OFFICE METHOD AND MEANS FOR AIR v CONDITIONING Francis R. Bichowsky, Ann Arbor, Mich.

Application August 21, 1940, Serial No. 353,573

15 Claims.

This invention relates to improved methods of conditioning air and apparatus therefor. More specifically the invention is concerned with an improved method of controlling the temperature, the humidity and the purity of air.

The present invention, then, comprehends a closure such as a room may be exercised. A further object of the invention is to provide automatic and efficient means for the control of the hereinbefore-mentioned apparatus. A primary object of the invention is to provide an apparatus which completely conditions the air in buildings in winter and/or summer.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the methods and means hereinafter fully described and particularly pointed out in the claims, the annexed drawings and the following description setting forth in detail certain methods and means for carrying out the invention, such disclosed erator. From the purge chamber It the absorbent solution is passed through the outlet l5 into a vaporizer chamber i6 and is broken up into methods and means illustrating, however, but several of various ways in which the principle of the invention may be utilised.

In said annexed drawings: Figure 1 is a crosssectional elevation of a specific embodiment of the principle of the present invention. Figure 2 is a diagrammatic modification of a specific embodiment of the principle of the present invention. Figure 3 is a portion of a psychrometric chart illustrating graphically a specific example of the process.

In Figure 1: Air is conditioned by withdrawing it from an enclosure through the duct 6, passing it through a conditioning chamber 8 and ejecting it into an enclosure from the duct 1.

. Air entering by the duct 6 is sprayed with an absorbent solution, i. e., lithium chloride, calcium chloride, etc., descending from the distributors 9. The air is then passed through a filter in and returned to the enclosure.

The absorbent solution, after descending fromthe distributors 9, collects in a sump H and is passed through a pipe l2 into a pipe 52 and thence into a purge chamber I 4'. The purge chamber I4 is part of a vacuum absorption refrigdroplets and distributed therein bythe distributing device H. A portion of the absorbent solution then collects in the sump l8 formed in the bottom of the vaporizer chamber l6. The vaporizer chamber I6 is insulated from the absorber chamber 19 by the space 20 therebetween and vapor flows from the vaporizer chamber I 6 to the absorber chamber l9 through the passage 2|. A jet evacuator 23 is disposed in the pipe 24. The vacuum thus produced in the purge chamber 14 serves to keep said chamber at lower than atmospheric pressure as well as to remove entrained I air from the absorbent solution, thus increasing the efficiency of the vaporizer chamber I6. A refiector 33 is placed in the chamber l6 above the opening into the absorber chamber l9 so as to reflect any heat originating in the absorber chamber l8 into the latter.

A sump 25 is formed on the floor of the ab sorber chamber l9. Absorbent solution reaching the distributor'26 is pumped from the sump 25 by' means of the pump 29 through the pipe 21. The sump 25 communicates with the pump chamber 29 by the opening 3|]. The major portion of the absorbent solution passing from the pump 29 through the pipe 21 is thus returned to the distributor 26 by means of the pipe 28. The absorbent solution then flows through the distributor 26 onto a cooling coil 3| and absorbs solvent vapor coming into'the absorber chamber l9 from the vaporizer chamber l6 by means of the passage Zl. This solution is then collected in the sump 25 for recirculation. Mounted on the motor 16 is a vacuum pump H which draws en- I trained air from the absorber l a through the pipe I2 and discharges this air to the atmosphere by the pipe 13. The pipe I2 leads from near the bottom of the absorber l 9 since, due to the sweep of water vapor from the chamber I 6, most of the air will tend to accumulate near that point.

The minor portion of the'solution flowing in the pipe 21 is passed by the pipe 32 into a sump 51 and thence by the pipe 35 through the heat exchanger 34 into the regenerator-condenser chamber 31 where it is distributed by a distributing device 38 over a heating coil 36. The condensing vapor in the heating coil 36 preferably has a boiling point somewhat higher than that of the absorbent solution at the highest concentration utilised. This solution flowing over the heating coil 36 is, thus, boiled and some of the solvent vaporized thereby. The solution thus concentrated by removal of solvent vapor and purified by the removal of noisome odours contained therein is passed by the pipe 39 through the heat exchanger 34 and the pipe (ill to the inlet of the pump 29 in the absorber chamber $9. In the pump chamber the concentrated solution and the solution entering by the opening 38 are mixed and passed through the pipe 2? in the manner previously described.

In reference to the material utilised in the heat ing coil 36, steam has been found to serve satis factorily but a stable organic liquid boiling from about 155 C. to about 175 C. is preferred. Examples of such liquids are brombenzene and orthodichlorobenzene. The vapors to be condensed may be drawn from any source such as the steam line of the building or produced in a boiler as shown. In the particular embodiment illustrated, the boiler 42 is providedwith a finned tube M protruding from the base of the boiler over a burner 43 connected to a source of fuel 44 fitted with a valve 45. Flue gases are vented by the stack 46. The liquid to be vaporized is contained in the boiler 41, a portion of the same passing down into the partially finned pipe ll and va porizing therein. The vapor thus produced then passes through the outlet 48 and collects in the upper portion of the hereinbefore-mentioned boiler 41 and is forced by the resulting pressure into a heating coil 36 in the regenerator-condenser chamber 31. After condensation the drips pass out of the heating coil 36 and are collected for re-utilisation in the boiler 41. Further details of the apparatus are disclosed in the followin description of the operation thereof.

Under average summer conditions it is generally desirable to maintain a low relative humidity and a temperature to adjust the condition of the air of the building to what are known to those skilled in the art as "comfort conditions. Automatically to maintain the temperature and relative humidity at their predetermined values a thermostat 49 and a humidostat ii-are provided. The purpose of the thermostat 49 is to actuate a control circuit when the temperature exceeds the predetermined range and to actuate a second control circuit when the temperature reaches a point below the lower limit of said predetermined range. The humidostat functions in the same manner to regulate the relative humidity. Thus, if the temperature in the building being conditioned rises above the upper limit a valve 5| in the pipe 52 is closed or partially closed so that a lesser amount of the absorbent solution leaving the sump II flows back thereto by the pipe l2, the pipe 52, the pipe 53, the pump 54, the jet evacuator 23, the pipe 55, and the distributors 9. The immediate result of this action is that more of the warm liquid leaving the sump H is passed by the pipe 52 into the chamber 14 and thence into the vaporizer chamber it where a portion of the solvent of the weak absorbent solution evaporates in the high vacuum therein obtaining, thus cooling the remaining absorbent solution. Thus, since less warm liquid is being returned to the sump and a greater relative portion of cooler liquid is entering therein, the temperature of the air being passed therethrough is lowered and the condition which originally caused the function is obviated. Should the relative humidity in the building being conditioned rise above the upper limit desired, the humidostat 50 automatically partially or wholly closes the valve 58 in the pipe 58 which enters the sump 51 thus decreasing the flow of liquid from I the sump 51 throughth e pipe 59, the pipe ther effect of the flow of solution of increased strength is to raise the level of the liquid in sump H, the excess liquid therein overflowing by the pipe 60 into the sump 5?. A second function served by the overflow pipe 5a is to accommodate the increase in volume of the liquid the sump it produced by the absorption of water from air. The combined action of these two effects is, while the unit is absorbing moisture, to weaken the liquid in the sump 5?. As the absorbent solution in the sump 5i becomes weaker its boiling point falls farther and farther below the temperature of the heating medium in the regenerator heating coil thus the absorbent liquid flowing over said heating coil has more and more water removed therefrom, the condensed vapor thereby resulting going to waste by means of pipe 69 and carrying therewith noisome odours while the non-boiling liquid flowing to the sump 5? by the pipe 39 and the pipe 35 is maintained at substantially constant concentration regardless of the overflow of absorbent liquid from the sump H due to the absorption of moisture from the building being conditioned.

It has been found that by means of this system of simultaneous control of humidity and temperature it is possible to operate with absorbent solutions of much less strength than have been necessary heretofore. For example. to maintain a relative humidity of 50% and a temperature of 80 F. in a building, it has usually been necessary or advisable to use in the scrubber solutions of very high concentrations, 1. e., those having a drying power capable of reducing the relative humidity of air in contact with them to as low as 15% relative humidity. In the practice of the present invention it is possible to dispense with the use of these highly concentrated solutions and to use cheaper solutions, e. g., calcium chloride instead of lithium chloride, capable of giving air a relative humidity of only about 50%. This advantage obtains because by using relatively cold solutions for dehumidiiication, the dew point of the air passing in contact with a solution of a given concentration is much lower than where solutions are employed having approximately room temperature.

Under winter conditions the temperature of the air may fall below the minimum setting of the thermostat 49 thus actuating a valve 45 increasing the supply of fuel to the burner 13 through the pipe 44. The same actuation shuts down the flow of cooling water through the pipe 63 by means of the valve 62. The combination of increased heating and decreased cooling raises the temperature of the liquid leaving the pump 29 so that the refrigeration cycle previously described is reversed and refrigerant vapor flows from the absorber chamber I9 to the vaporizer chamber l8 thusraising the temperature of the liquid flowing through the pipe 53 so that it heats the air flowing through the scrubbing chamber 8. If the humidity now falls midity of the air is increased because of the decreased concentration of the absorbent solution.

In the embodiment ofthe present invention illustrated in Figure 2 air is conditioned by withdrawing it from a room, passing it through a conditioning chamber 18 and ejecting it into a roomor other enclosure through the .duct 15. One or more distributors 19 for absorbent solution are provided in, the conditioning chamber or scrubber 18. A sump 80 is provided to collect the absorbent solution descending from the distributors I9. A-float valve 8| is provided to control the introduction of additional water from the main 8! should the level of liquid in the sump 89 fall below a predetermined point. This same float valve may also be so disposed as to close the outlet line 83 from the sump 80 thus preventing air from being drawn intothe pipe 83 in case of a dearth of liquid in the sump 80. In orderto prevent too rapid a flow of liquid through the pipe 83 into the vaporizer chamber 8 a reducing valve 85 is introduced into said pipe. One or-more distributors 86 are provided in the vaporizer chamber 84 similar to those provided in the scrubber l8, and adapted to disperse the liquid entering th'ereinto in a fine spray so that at least a portion of .said liquid-is evaporated under the vacuum obtaining in said chamber. Some of the absorbent solution entering the vaporizer chamber 84 by the distributors 85 collects in a sump 81 formed in the bottom of said chamber. The liquid utilised in this portion of theapparatus may be a solution of any suitable absorbent, e. g., calcium chloride.

The vaporized solvent obtaining in the vaporizer chamber 84 passes by the outlet 88 into an absorber chamber 89 where it is absorbed in a secondabsorbe'nt solution which enters the.absorber chamber 89 by means of the distributors 90. Cooling ,coils 9i are provided for the dual purpose of taking up the heat of absorption and providing an absorption surface. The second absorbent solution, now diluted by the addition centrated solution in the regenerator chamber I09 is, then, passed back into the absorber sump 92 by the pipe II! to be circulated through the pipe 93, the pump 94, etc., in the manner pre-,

viously described. A valve, not shown, of the type well known in the art may be provided in the line ill to prevent vapor passing from the regenerator chamber IN! to the absorber chamber 89. In the preferred embodiment of the present invention the cooling water in the coil H0 in the condenser chamber 108 may be that leavingthe cooling coll 9| in the absorber chamber 89. Such a procedure has been found to facilitate control of the apparatus to a considerable degree.

Air entering the-evaporator chamber 18 has been found to dissolv in the solution leaving said chamber. For this reason a purge line 5 operably connected to a steam jet evacuator H2 in the present embodiment has been provided to maintain a vacuum in the vaporizer chamber 84 and the absorber chamber 89 and to remove the dissolved and entrained air from the absorbent solution.

It has been found convenient to operate the regenerator chamber I00 and condenser chamber Hi8 at pressures below atmospheric while the pressures in the vaporizer chamber 84 and the absorberchamber 89 are substantially under a high vacuum.

A humidistat H6 is provided in the room or enclosure from which air is being conditioned and said instrument is connected so that whenof solvent, is collected in a sump 92 formed in the bottom of the absorber chamber 89. This solution is, then, withdrawn by the pipe 93,

' passed throughthe pump 94 and into the pipe 95 where the major portion-is passed into the pipe 96, through the reducing valve 99 and back into the absorber chamber 99 by means of the distributors 90. The remainder of the solution is passed through the pipe 91, the control valve 98 and into a regenerator chamber'lllli by means ofthedistrib utors Ml therein. This solution is then passed over a calandria I02. Steam for the calandria I92 is obtained by means of the pipe I93 from the steam line I94. Drips are ,collected and passed oil by the pipe I95. This condensate may be returned to the hot water boiler by the valve I95 or othenmeansmot shown.

The absorbent solution collecting in the sump ZQ'I in the bottom of the regenerator chamber I00 "isnow, concentrated since a portion of the solvent has been driven off as vapor and is passed into a condenser chamber I08 through the conduit 9 and condensed ,on the cooling coils ill to be passed into the purge line I ll through the pipe III and the jet evacuator H2. The convaporizer-scrubber cycle.

ever the humidity in the enclosure becomes lower than the predetermined value, water enters the sump 80 by the opening of the valve I IS. A thermostat H1 is provided and connected so that when the temperature becomes too high in the enclosure, a valve 98 is opened permitting more solution to flow to the regenerator chamber I00.

The absorbent liquid employed in the absorber and condenser chambers is, preferably, an abs'orbent of greater absorbent power than that utilised in the vaporizer and scrubber chambers, e. g., a concentrated solution of zinc chloride, but, if it is desired, the solutions in the two cycles may be of the same solute providing the solution in the absorber-regenerator cycle is maintained at a higher concentration than that in the Figure 3 is a chart of the partial pressure of water vapor (in logarithmic scale) as ordinate and temperature (in arbitrary scale) as abscissa. Point A represents the temperature and partial pressure of water vapor in air of 80 F. and relative'humidity (0.42 inch of mercury).

As an illustrative example of the process of the invention air of this state, which may be air from the enclosure, or fresh air, or a mixture of fresh air and air from the enclosure, is led into contact with a solution of calcium chloride which is at a temperature of F. and a partial pressure of 0.26 inch, and which is about 32% 'concentrated. Such a solution has the state indicated on the chart by the point C. Due to the contact of the scrubbing solution of calcium chloride with air of stateA, the air in the example is cooled to F. and attains a vapor pressure of 0.31 inch. Air of this state, B. is returned to the enclosure where it picks up heat and moisture, returning after admixtur to state. A thus maintaining an enclosure in comfort conditions.

The solution at state C entering contact with the air at state A picks up moisture and is warmed to the state D in the example. 62' I". and

' .027 inch; solution in the state D is then ad- 0.29 inch. Solution of the state E is then con-J centrated and colled to the state C by, for example, being passed into an evacuatedchamber sothat the solution (state E) bolls and cable.

This vacuum may be maintained by absorbing the water vapor produced by the evaporation of solution in state E, the vapor being absorbed 'into a strong solution of state F, 90 F. and 0.16 inch, which, for' example, is the state of a solution of zinch chloride having a density of 2.0 .i1% concentration). Becauseof the absorption of water vapor by strong solution of state F, heat is given to the solution which is diluted. It is convenient to cool the strong solution during or after this step, the solution, after cooling, having the stateG, 90 F. and 0.19 inch. In order to maintain the strong solution in the state F. it

is convenient to withdraw a portion ofthe strong solution at some point for example the state H, 93 F. and 015 inch, througha heat exchanger and to concentrate the withdrawn portion by boiling ofl apart of the water, conveniently at atmospheric pressure, at 298 F. (a state not shown on Figures), and returning the concentrated solution to the-state J, 94 F. and 0.14 inch, the solution of state H being obtained by mixing solution of state G with solution of.

state J. v

Other modes of applying the principle of this invention may be employed insteadof those explained, change being made as regards the meth- I ads and means herein disclosed, provided those stated by any of the following claims or their equivalent is employed.

I therefore particularly pointou't and distinctly claimas my invention:

l. The method of modifying the temperature and humidity of airv which comprises the steps of passing a primary absorbent solution in contact with air, passing said primary absorbent solution through an evacuated zone wherein va portion ofthe solvent-is vaporized, absorbing said "vaporized solvent in a solution of secondary absorbent, mix 'ing a portion of said secondary absorbent with and recontacting mixed said primary absorbent, absorbent with air.

2. The method of modifying the temperature" and humidity of air which comprises the steps of aavasoo" transferred by flow induced by vapor pressure dii-' ferenoe from said evacuated zone to said absorption zone, circulating secondary absorbent solution'from said absorption zone, circulating a portionofsaid secondaryabsorbent solution into a heating zone, and returning the balance of said secondary absorption solutionto said absorption zone.

4. The method of regulating the vapor pressure and temperature. of a body of aqueous solution of an absorbent which comprises the step of trans. ferring vapor in a vacuum in the absence of an inert gas betweensaid first body of aqueous solution and a secondbody of aqueous solution of "tween said primary absorbent stream and a secthe same absorbent, said second solution having a-difi'erent strength, so as to-maintain said first body at a predetermined temperature; and transferring a. portion ofsolution between said bodies so as to maintain the first mined. strength.

5. Themethod of modifying the temperature and humidity of the air which comprises the steps of contacting ,a body of air with a primary stream of an absorbent solution, changing the temperature of said primary stream of absorbent by transferring by fiow due to vapor pressure difference of said primary absorbent and said secondary absorbent water vapor in a vacuum beondary stream of said absorbent at a diiferent concentration; and regulating strength of said primary stream of absorbent by transferring liquid absorbent between said primary stream and said secondary stream.

ii. The method of dehumidifying and cooling air 4 which comprises the steps of contacting the air 1 with a cool solution of-a dehumidifying agent,

passing a primary absorbent solution in contact with air, passing said primary absorbent solution through'an evacuated zone wherein a portion'oi' the solvent is vaporized, passing said vaporized solvent through an absorption zone in contact of said absorptionzone, recirculating a portion of said mixture. into said absorption zone, the remainder of said mixture into a heating zone wherein a portion of the solvent is vaporized out of the liquid passed thereinto, returning yvaporized portion of solution from the zone to the absorption zone, mixing a Portion of said secondary absorbent with said primary ab- I sorbent the un heating it and contacting the resulting mixture with a 1 1 with a'secondary absorbent, passing the secondary absorbent-solvent mir kture thus produced out evaporating in a vacuum from said solution a portion of the water-therein thus cooling said so-,

lstion, transferring by natural flow, absorbing in a vacu the water vapor so produced in a secand body of absorbent solution, heating a portion of said second body of solution so as to evaporate water therefrom, discarding said water, cooling said heated solution and returning it forre-use in absorption; returning the first body of solu-- tion, after cooling for re-use incontact with air.

7. The method of heating and humidifying'air comprising the steps of contacting air with a hot body of absorbent solution thereby heating and humidifying said air, removing the resulting body oi 'warm solution from contact with the air, evaporating water from a second body of solution and condensing it in said first body so as to heat said first body of solution transferring a portion or said first body of solution tosaid second body of solution and adding water to said solution and contacting the resulting solution with more air to 'be heated and humified.

,8. Themethodzof controlling the condition of tasting-the air in said enclosure with a primary air in an enclosure, comprising the steps of con 1 of absorbent solution, transferring water vapor in'an evacuated chamber from said primary body ofthe solution to asecondary body of absorbent solution whenever the temperature in said enclosure exceeds a predetermined value, transferring water-vapor in a vacuum from said secondarybody of solution to said primary body of solution-whenever the temperature in said en- I closure falls below a certain value, increasing the concentration of the primary solution whenever the humidity'in the enclosure exceeds a certain value and transferring moisture to said primary body at a predeterbody of solution whenever the humidity in said enclosure falls below a predetermined value.

9. The method of conditioning air which com- 7 prises the steps of contacting air with a primary absorbent solution, automatically controlling the temperature and concentration of said solution,

exchanging moisture between said primary solution and a secondary solution of an absorbent by flow induced by vapor pressure cliiference of said primary and said secondary solution of absorbent, automatically controlling the temperature and concentration of said secondary solution.

10. Apparatus for air conditioning including an evacuated chamber, means for spreading an absorbent liquid therein, second evacuated chamher, said regenerator chamber being maintained said means including condensing a liquid having a at atmospheric pressure, means for heating said absorbent stream in said regenerator chamber,

. midostat, means for conveying a portion of said her connected with the first, means for distributing a, second stream of absorbent liquid therein, a, third chamber, meansfor distributing a portion of the stream of absorbent liquid from said second chamber therein, means for heating said absorbent liquid for said third chamber, a sump, means for conveying liquid to and from said sump means for conveying a portion of a, stream of liquid in said second evacuated chamber to said second sump, means for conveyinga portion of the liquid from said second sump to said third chamber and of returning liquid from said third means for controlling the addition of water to the first sump, mean for controlling the inter-- change of liquid between said sumps so as to regulate the liquid in said first sump at a predetermined concentration and temperature.

' to said first evacuated chamber, a secondsump;

11. Air conditioning apparatus including an enclosure, a thermostat and a humidistat in said enclosure, means for introducing air into said enclosure, means for drawing air from said enclosure, means ior treating a portion of the air withdrawn from said enclosure ,with a solution water vapor between said absorbent and another stream of said absorbent dispersed in a second evacuated chamber in communication with said first evacuated chamber, means for circulating a portion of said liquid in said second evacuated chamber for re-use in said chamber, means for circulating a. portion of said stre'amjrom said second evacuated chamber to a. regenerator chamliquid from said first stream to said second stream,

said means being under control of the thermostat,

means for supplying heat,said means being under control of said thermostat.

12. In a vacuum absorption refrigerator a single container including an evaporator section, an absorber section situated below and communicating with said evaporator section through an open throat, inclosed in said absorber section a totally enclosed motor in operative relation to a pump, said pump being adapted to remove liquid absorbent from said absorber, below said absorber and sealed therefrom, a regenerator section,

means for passing liquid irom said absorber to said regenerator.

13. In a vacuum refrigerator of the absorption type, a regenerator, a condenser, ,a boiler containing'an organic; liquid with normal boiling point slightly above the boiling point of an absorbent at a predetermined concentration and pressure, means for conveying vapor from said boiler into 'thermal contact; with said absorbent in said regenerator and condensing said vapor, mean for returning said condensate to' said boiler, said boiler and said regenerator being operated at 'approximately atmospheric pressure. I

14. Apparatus for conditioning air temperature and humidity, comprising air-liquid contact means, an evacuated vaporizer, a purge chamber, and means for purging air from liquid in said purge chamber, means for passing liquid from said air-liquid contact means to the purge cham contacting chamber wherein said air is contacted witha primary absorbent solution, an evacuated chamber, a secondary body of absorbedsolution,

said evacuated chamber comprising two parts, means in one part for evaporating a portion of said absorbent solution, means in the second part for absorbing said evaporated portion, a, passage allowing free unidirectional flow from one part to the other of said parts.

, FRANCIS R. BIcHowsKY'. 

